1. Field of the Invention
This invention relates generally to methods, systems and apparatus for managing digital communications systems. More specifically, this invention relates to a DSL system using multiple loops in a coordinated manner to provide high speed communications.
2. Description of Related Art
Digital subscriber line (DSL) technologies provide potentially large bandwidth for digital communication over existing telephone subscriber lines (referred to as loops and/or the copper plant). Telephone subscriber lines can provide this bandwidth despite their original design for only voice-band analog communication. In particular, asymmetric DSL (ADSL) and very-high-speed DSL (VDSL) can adapt to the characteristics of the subscriber line by using a discrete multitone (DMT) line code that assigns a number of bits to each tone (or sub-carrier), which can be adjusted to channel conditions determined during initialization and subsequent on-line training known as “bit-swapping” of the modems (typically transceivers that function as both transmitters and receivers) at each end of the subscriber line.
Currently, VDSL2 systems can achieve data rates of up to approximately 150 Mbps on short loops and ADSL2+ systems can achieve data rates of up to approximately 25 Mbps on somewhat longer loops than VDSL. “Short loops” are loops in which the component wires are preferably approximately 100 meters or less, and certainly 300 meters or less. Higher data rates are generally prohibited due to the line attenuation, but on short loops are particularly limited by the maximum bandwidth used by the ADSL and VDSL modems and by frequency selective noises caused by crosstalk from other phone lines sharing the same cable, radio ingress, and a variety of customer-premises noises often known generically as impulse noise. These short loops are found at various points in a typical DSL plant.
Systems, methods and techniques that permit higher data rates without having to extend optical fiber and other high bandwidth materials to customer premises and the like would represent a significant advancement in the art.